1. Field of the Invention
The present invention relates to an electro-optical panel in which an electro-optical material, such as liquid crystal, is sealed between a pair of substrates, to a projection display apparatus using the electro-optical panel, and to an electro-optical panel production method. More particularly, the present invention relates to a technique for ensuring a predetermined gap between a pair of substrates.
2. Description of Related Art
As shown in FIG. 19 and FIG. 20, an electro-optical panel, in which an electro-optical material, such as liquid crystal, is sealed between a pair of substrates, generally comprises a thin-film transistor (hereinafter referred to as xe2x80x9cTFTxe2x80x9d) array substrate (transistor array substrate) 2 in which pixel electrodes 8 and TFTs 10 for pixel switching are formed on the surface of a tansparent substrate made of silica glass or the like, a counter substrate 3 in which counter electrodes 32 are formed on the surface of a glass substrate having high heat resistance, such as Neoceram, and an electro-optical material 39, such as liquid crystal, sealed and held between the substrates as shown in FIG. 19 and FIG. 20. The TFT array substrate 2 and the counter substrate 3 are bonded with a predetermined gap therebetween by a sealing material 200xe2x80x2 containing a gapping material, and an image display region 37 having the electro-optical material 39 sealed therein is divided in the gap by the sealing material 200xe2x80x2. Conventionally, an epoxy resin or acrylic resin adhesive component, with which glass beads or the like are mixed as a gapping material, is used as such a sealing material 200xe2x80x2 containing a gapping material.
In the electro-optical panel 1xe2x80x2 thus configured, the alignment state of the electro-optical material 39 is controlled pixel-by-pixel between the pixel electrodes 8 and the counter electrodes 32 according to image signals applied to the pixel electrodes 8 via data lines (not shown) and the TFTs 10 on the TFT array substrate 2, thereby displaying a predetermined image corresponding to the image signals. Therefore, in the TFT array substrate 2, it is necessary to supply image signals to the pixel electrodes 8 via the data lines and the TFTs 10, and to also apply a predetermined potential to the counter electrodes 32.
Accordingly, in the electro-optical panel 1xe2x80x2, a first electrode 47 for continuity between the substrates is formed on the TFT array substrate 2 by using a process for forming data lines, a second electrode 48 for continuity between the substrates is formed on the counter substrate 3 by using a process for forming the counter electrodes 32, and the first electrode 47 and the second electrode 48 for continuity between the substrates are electrically conducted by a conducting member 56 obtained by mixing an epoxy resin or acrylic resin adhesive component with conductive particles such as silver powders and gold-plated fibers. For this reason, in the electro-optical panel 1xe2x80x2, predetermined signals can be input to both the TFT array substrate 2 and the counter substrate 3 by connecting a flexible wiring board 99 or the like only to input and output terminals 45 of the TFT array substrate 2, instead of connecting a flexible wiring board to both the TFT array substrate 2 and the counter substrate 3.
Although attempts have been made to improve display quality by reducing the gap (cell gap) between the TFT array substrate 2 and the counter substrate 3 to approximately 2 xcexcm in the electro-optical panel 1xe2x80x2, if such a small cell gap is ensured only by the gapping material contained in the peripheral sealing material 200xe2x80x2, it varies substantially because it is small. As a result, the layer of the electro-optical material 39 significantly varies in thickness, and therefore, the display screen becomes unnaturally bright and dark and the response speed of the electro-optical material 39 varies. This deteriorates display quality on the contrary.
Accordingly, a structure may be conceived in which the cell gap is controlled by scattering spacers in the image display region 37. However, when the electro-optical panel 1xe2x80x2, in which the spacers are scattered throughout the image display region 37, is used in a projection display apparatus, since light transmittance is reduced at the portions where the scattered spacers are dense, such defects are magnified and projected onto a screen.
In consideration of the above problems, an object of the present invention is to provide an electro-optical panel in which the gap is precise and is uniform over the entire image display region, a projection display apparatus using the electro-optical panel, and an electro-optical panel production method.
In order to overcome the above problems, the present invention provides an electro-optical panel wherein an electro-optical material is held between a pair of substrates, the pair of substrates are fixedly bonded by a sealing material, and an image display region composed of a plurality of pixels is formed inside an area where the sealing material is formed, and wherein one of the pair of substrates has a protrusion projecting into contact with the other substrate, and the protrusion is formed in an area surrounding the pixel region.
In this invention, since the gap (cell gap) between the substrates is controlled by contacting the protrusion formed on one of the substrates with the other substrate, it is possible to control the gap more precisely than in a structure in which the gap is controlled by a gapping material contained in the sealing material. Since the protrusion is formed to surround the image display region, it is possible to avoid variations in the gap between the substrates over the entire image display region. For this reason, it is possible to achieve an electro-optical panel in which the gap is precise, even if the gap is small, and is uniform over the entire image display region. Since it is unnecessary for the sealing material to contain the gapping material, even when wires are disposed on the lower side of the sealing material, they can be prevented from being crushed and broken by the gapping material.
In this invention, for example, the protrusion may be formed along one of an inner peripheral edge and an outer peripheral edge of the sealing material formation area
In this invention, it is preferable that the protrusion include a first protrusion formed along the inner peripheral edge of the sealing material formation area, and a second protrusion formed along the outer peripheral edge, and that the sealing material be formed in an area disposed between the first protrusion and the second protrusion. Since the sealing material is blocked by the first protrusion and the second protrusion in such a structure, even when unset sealing material is applied or when the sealing material is heated, it does not extrude into an undesirable area. For this reason, a thermosetting sealing material can be used.
According to another aspect, the present invention provides an electro-optical panel wherein an electro-optical material is held between a pair of substrates, the pair of substrates are fixedly bonded by a sealing material, and an image display region composed of a plurality of pixels is formed inside a region where the sealing material is formed, and wherein one of the pair of substrates has a protrusion projecting into contact with the other substrate, and the protrusion is formed around a formation region of a conducting members for electrically connecting conductive layers respectively formed on the pair of substrates.
For example, it is preferable that the protrusion be formed to surround the conducting member. In such a structure, since the conducting member is blocked by the protrusion, when an unset conducting member is applied or when the conducting member is heated, it does not extrude into an undesirable area. For this reason, a thermosetting adhesive component can be used for the conducting member.
The sealing material may be formed so that at least a part thereof overlaps with a shielding film formed on the periphery of the image display region. In such a structure, since the sealing material is extended to the shielding film, adhesion of the sealing material can be enhanced.
In this invention, it is preferable that the protrusion be made of an elastically deformable material and be depressed between the pair of substrates. In such a structure, a force for enlarging the space between the substrates is applied so that the depressed protrusion returns to its initial shape, whereas the substrates are fixed by the sealing material. Therefore, the gap between the substrates can be made uniform.
In this invention, the pair of substrates may include, for example, a transistor array substrate having pixel electrodes and thin-film transistors for pixel switching formed in a matrix, and a counter substrate having counter electrodes.
In a projection display apparatus (electro-optical device) using such an electro-optical panel, there are placed a light source, a light-collecting optical system for guiding light emitted from the light source to the electro-optical panel, and a magnified projection optical system for magnifying and projecting light modulated by the electro-optical panel.
In an electro-optical panel production method of the present invention, the protrusion is formed on one of the pair of substrates, and the sealing material is then applied and set while pressing the pair of substrates.
In the electro-optical panel production method of this invention, preferably, a first protrusion and a second protrusion are formed along the inner peripheral edge and the outer peripheral edge of an area where the sealing material is to be formed, and the sealing material is applied in an area placed between the first protrusion and the second protrusion, and is set while pressing the pair of substrates. In such a structure, when an unset sealing material is applied, it is blocked by the protrusions and does not extrude into an undesirable area.
In the electro-optical panel production method of this invention, preferably, after the protrusions are formed to surround an area where the conducting member is to be formed, the conducting member is applied in the area surrounded by the protrusions, and the sealing material and the conducting member are simultaneously or separately set while pressing the pair of substrates. In such a structure, when an unset conducting member is applied, it is blocked by the protrusions and does not extrude into an undesirable area.
In the electro-optical panel production method of this invention, preferably, the protrusions are made of an elastically deformable material on one of the substrates, the sealing material is applied on the substrate, the protrusions are elastically deformed by pressing the pair of substrates, and the sealing material is set in this state.
The present invention also provides an electro-optical panel wherein an electro-optical material is held between a pair of substrates, the pair of substrates are fixedly bonded by a sealing material, and an image display region composed of a plurality of pixels is formed inside an area where the sealing material is formed, and wherein one of the pair of substrates has protrusions projecting into contact with the other substrate, and the protrusions are scattered at predetermined positions in the image display region.
In this invention, since the gap (cell gap) between the substrates is controlled by contacting the protrusions formed on one of the substrates with the other substrate, it is possible to control the gap more precisely than in the structure in which the gap is controlled by the gapping material contained in the sealing material. Since the protrusions are formed to be scattered throughout the image display region, the gap between the substrates does not vary over the entire image display region. For this reason, it is possible to achieve an electro-optical panel in which the gap is precise, even if the gap is small, and is uniform over the entire image display region. In such an electro-optical panel, even when the protrusions are formed in the image display region, they are not concentrated in particular areas. Furthermore, since it is unnecessary for the sealing material to contain the gapping material, even when wires are disposed on the lower side of the sealing material, they can be prevented from being crushed and broken by the gapping material.
In this invention, it is preferable that the protrusions be formed in non-aperture areas, which do not transmit light, of the respective pixels formed in the image display region. In such a structure, even when the protrusions are formed in the image display region, they are not projected on a display. Accordingly, this invention is effective when using the electro-optical panel as a light valve in a projection display apparatus.
In this invention, it is preferable that the protrusions be formed at the same point in the respective pixels formed in the image display region. That is, it is preferable that the protrusions be formed at the same coordinates in the respective pixels. In such a structure, since the protrusions are formed at the same height in the pixels, it is possible to make the gap between the substrates more uniform. For this reason, even when an uneven substrate is used, a constant gap can be ensured between the substrate and another substrate.
In this invention, it is preferable that the protrusions be cylindrical. In such a structure, when an electro-optical material, such as liquid crystal, is filled, it smoothly flows along the protrusions, so that insufficient filling of the electro-optical material does not occur.
In this invention, it is preferable that the protrusions be formed at a higher density in the peripheral area of the image display region than in the central area. In such a structure, the center of the panel sometimes bulges according to the timing at which the electro-optical material, such as liquid crystal, is injected between the substrates. It is preferable to bond the substrates in anticipation of such a bulge. That is, the gap between the substrates is small in the central area of the image display region immediately after the substrates are bonded, whereas the central area bulges when the electro-optical material is injected into the image display region. Even if the gap in the area increases slightly, such an increase is absorbed and reduced by the difference in gap before the electro-optical material is injected. For this reason, it is possible to make the gap between the substrates uniform over the entire image display region.
In this invention, it is preferable that the protrusions be formed at a higher density in one area of the image display region than in another area. When producing the electro-optical panel of this invention, protrusions are formed on one of the substrates, and a sealing material is applied and is set while applying a force to reduce the gap between the pair of substrates. In a case in which an area, where the force always increases or decreases when pressing the substrates, is known, the protrusions are formed at a density sufficient to absorb and reduce the increase or decrease. That is, since the protrusions are formed in a predetermined distribution on one of the substrates based on the aptness of a device for bonding the substrates, it is possible to make the gap between the substrates uniform over the entire image display region.
In this invention, it is preferable that the protrusions be made of an elastically deformable material and be depressed between the pair of substrates. In such a structure, a force for enlarging the space between the substrates is applied so that the depressed protrusions return to their initial shape, whereas the substrates are fixed by the sealing material. Therefore, the gap between the substrates can be made uniform.
In this invention, the pair of substrates may include, for example, a transistor array substrate having pixel electrodes and thin-film transistors for pixel switching formed in a matrix, and a counter substrate having counter electrodes.
In a projection display apparatus (electro-optical device) using such an electro-optical panel, there are placed a light source, a light-collecting optical system for guiding light emitted from the light source to the electro-optical panel, and a magnified projection optical system for magnifying and projecting light modulated by the electro-optical panel.
In an electro-optical panel production method of the present invention, after the protrusions are formed on one of the pair of substrates, the sealing material is applied and set while pressing the pair of substrates.
In the electro-optical panel production method of this invention, preferably, after the protrusions are made of an elastically deformable material on one of the substrates, the sealing material is applied on the substrate, the protrusions are elastically deformed by pressing the pair of substrates, and the sealing material is set in this state. In such a structure, a force for enlarging the space between the substrates is applied so that the depressed protrusions return to their initial shape, whereas the substrates are fixed by the sealing material. Therefore, the gap between the substrates can be made uniform.
The present invention provides an electro-optical panel wherein an electro-optical material is held between a pair of substrates, the pair of substrates are fixedly bonded by a sealing material, and an image display region composed of a plurality of pixels is formed inside a region where the sealing material is formed, and wherein one of the pair of substrates has a protrusion projecting into contact with the other substrate, and the protrusion is formed to face a shielding film formed in an area surrounding the pixel region.
According to this invention, since the gap (cell gap) between the substrates is controlled by contacting the protrusion formed on one of the substrates with the other substrate, it is possible to control the gap more precisely than in a structure in which the gap is controlled by the gapping material contained in the sealing material. Since the protrusion is formed to surround the image display region, it is possible to avoid variations in gap between the substrates over the entire image display region. Furthermore, since the protrusion is formed to face the shielding film, it is possible to provide the protrusion while effectively using a non-display region.
In this invention, the protrusion may be placed within the width of the shielding film in plan view. According to this invention, since the protrusion is placed within the width of the shielding film in plan view, it is possible to prevent the protrusion from affecting the display region.